In the following diagram, suppose that the green cross bar is moving to the right at a constant velocity, v. As it moves, the area of the "loop" presented to the magnetic field (+z) increases consequently allowing more flux lines to pass through the "loop" and generating an emf in the "loop."

ε = -N(ΔΦ/Δt)

ε = -N (BperpendicularΔA) /Δt

ε = -NBperpendicular (Δw) /Δt

ε = -NB perpendicular (Δw/Δt)

ε = -NB perpendicular v

and obeys the formula

motional ε = - NBperpendicularv

The right-hand curl rule is used to determine the direction of the induced emf/current. In this formula, v is the constant velocity in m/sec with which the loop is moving into or out of the magnetic field and is the length of the side of the loop which does not change.

As the bar moves to the right, will a clockwise or counterclockwise current be induced in the left side of the coil?

Calculate the amount of force required to keep the bar moving at a constant velocity.

As the bar moves to the right, calculate the amount of electrical power dissipated through the resistor.

We will now look at these two AP essays to verify that you understand the principles of induced emf.